Orientable whipstock tool and method

Abstract

A whipstock assembly includes a whipstock body 8 having a whipstock center of gravity offset radially from the central axis of the whipstock body, a counterweight to releasably secured to the whipstock body, with a counterweight having an offset counterweight center of gravity, an orientation device 5 , and a neutralizer 11 . The neutralizer causes the combined whipstock/neutralizer center of gravity to be substantially closer to the central axis of the whipstock body compared to the whipstock center of gravity. An attaching mechanism 6, 12 allows the neutralizer to be returned to the surface after the whipstock body is set in the well.

1. A whipstock assembly for positioning in a well bore at a selected azimuth, the whipstock assembly comprising:
 a whipstock body supporting an inclined whipstock face, the whipstock body having a whipstock center of gravity offset radially from a central axis of the whipstock body; 
 a counterweight releasably securable to the whipstock body, the counterweight having an offset counterweight center of gravity such that a portion of the counterweight tends to occupy a low side of the well bore; 
 an orientation device for selectively orienting the whipstock face at a selected rotational position relative to the counterweight; 
 a neutralizer releasably securable to the whipstock body, the neutralizer being positioned relative to the whipstock body such that a neutralizer center of gravity is radially opposite the whipstock center of gravity with respect to the central axis of the whipstock body, the neutralizer being removeably attached from the whipstock body; 
 a combined whipstock/neutralizer center of gravity is substantially closer to the central axis of the whipstock body than the whipstock center of gravity to reduce the mass of the counterweight; and 
 a detaching mechanism for selectively releasing the neutralizer from the whipstock body, such that the neutralizer may be returned to the surface after the whipstock body is set in the well. 
 
   
   
     2. A whipstock assembly as defined in  claim 1 , wherein the inclined whipstock face of the whipstock body intercepts a substantially cylindrical outer surface of the whipstock body, and the counterweight includes an outer substantially cylindrical surface with substantially the same diameter as the outer surface of the whipstock body. 
   
   
     3. A whipstock assembly as defined in  claim 1 , wherein the neutralizer includes an engagement surface for substantially planar engagement with the whipstock face when the neutralizer is secured to the whipstock body. 
   
   
     4. A whipstock assembly as defined in  claim 1 , wherein the neutralizer occupies a volume removed from the whipstock body during manufacture of the whipstock body. 
   
   
     5. A whipstock assembly as defined in  claim 1 , wherein one of a radially moveable key and whipstock body include tabs to prevent premature retraction of the key from the whipstock body. 
   
   
     6. A whipstock assembly as defined in  claim 5 , wherein a slot in the whipstock body includes a relief section to allow retraction of the key after the whipstock has been set in the well. 
   
   
     7. A whipstock assembly as defined in  claim 5 , wherein each of the key and a connector sub include mating shoulder to limit radially outward movement of the key. 
   
   
     8. A whipstock assembly as defined in  claim 1 , wherein shear pins limit movement of the neutralizer with respect to the whipstock body. 
   
   
     9. A whipstock assembly for positioning in a well bore at a selected azimuth, the whipstock assembly comprising:
 a whipstock body supporting an inclined whipstock face, the whipstock body having a whipstock center of gravity offset radially from a central axis of the whipstock body; 
 a counterweight releasably securable to the whipstock body, the counterweight having an offset counterweight center of gravity such that a portion of the counterweight tends to occupy a low side of the well bore: 
 a neutralizer releasably securable to the whipstock body, the neutralizer being positioned relative to the whipstock body such that a neutralizer center of gravity is radially opposite the whipstock center of gravity with respect to the central axis of the whipstock body; 
 a combined whipstock/neutralizer center of gravity is substantially closer to the central axis of the whipstock body than the whipstock center of gravity to reduce the mass of the counterweight; and 
 a detaching mechanism for selectively releasing the neutralizer from the whipstock body, such that the neutralizer may be returned to the surface after the whipstock body is set in the well. 
 
   
   
     10. A whipstock assembly as defined in  claim 9 , wherein the inclined whipstock face of the whipstock body intercepts a substantially cylindrical outer surface of the whipstock body, and the counterweight includes an outer substantially cylindrical surface with substantially the same diameter as the outer surface of the whipstock body. 
   
   
     11. A whipstock assembly as defined in  claim 9 , wherein the neutralizer includes an engagement surface for substantially planar engagement with the whipstock face when the neutralizer is secured to the whipstock body. 
   
   
     12. A whipstock assembly as defined in  claim 9 , wherein one of a radially moveable key and whipstock body include tabs to prevent premature retraction of the key from the whipstock body. 
   
   
     13. A whipstock assembly as defined in  claim 9 , wherein shear pins limit movement of the neutralizer with respect to the whipstock body. 
   
   
     14. A method of positioning a whipstock assembly in a wellbore at a selected azimuth, the method comprising:
 providing a whipstock face on a whipstock body, the whipstock body having a whipstock center of gravity offset radially from a central axis of the whipstock body; 
 releasably securing a counterweight to the whipstock body, the counterweight having an offset counterweight center of gravity such that a portion of the counterweight tends to occupy a low side of the wellbore; 
 releasably securing a neutralizer to the whipstock body, the neutralizer being positioned relative to the whipstock body such that a neutralizer center of gravity is radially opposite the whipstock center of gravity with respect to the central axis of the whipstock body, and the combined whipstock/neutralizer center of gravity is substantially closer to the central axis of the whipstock body than the whipstock center of gravity to reduce the mass of the counterweight; 
 running the whipstock body and the neutralizer in a well; and 
 selectively releasing the neutralizer from the whipstock body, such that the neutralizer may be returned to the surface after the whipstock body is set in the well. 
 
   
   
     15. The method as defined in  claim 14 , wherein an engagement surface on the neutralizer is in substantially planar engagement with the whipstock face when the neutralizer is secured to the whipstock body. 
   
   
     16. The method as defined in  claim 14 , further comprising:
 providing a radially moveable key, one of the key and the whipstock body including tabs to prevent premature retraction of the key from the whipstock body.